Load modulation detector

Abstract

An apparatus includes load modulation sensing circuitry configured to detect variations on a DC electrical current used by power transmission circuitry configured to be in wireless communication with power receiving circuitry of a device. The load modulation sensing circuitry configured to detect at least positive variations on the DC electrical current greater than or equal to a first threshold level, to detect at least negative variations on the DC electrical current greater than or equal to a second threshold level, and to process detected positive variations and detected negative variations to generate signals indicative of load modulation of the power receiving circuitry of the device.

1 . An apparatus comprising:
 load modulation sensing circuitry configured to detect variations on a DC electrical current used by power transmission circuitry configured to be in wireless communication with power receiving circuitry of a device, the load modulation sensing circuitry configured to detect at least positive variations on the DC electrical current greater than or equal to a first threshold level, to detect at least negative variations on the DC electrical current greater than or equal to a second threshold level, and to process detected positive variations and detected negative variations to generate signals indicative of load modulation of the power receiving circuitry of the device.   
     
     
         2 . The apparatus of  claim 1 , wherein the power transmission circuitry comprises inductive coupling circuitry and at least one power supply configured to provide the DC electrical current to the inductive coupling circuitry, the inductive coupling circuitry comprising at least one power transmission coil and coil driver circuitry configured to receive the DC electrical current and to provide driving electrical current to the at least one power transmission coil. 
     
     
         3 . The apparatus of  claim 2 , wherein the at least one power supply comprises at least one DC voltage and/or current source and at least one current sense resistor in series between the at least one DC voltage and/or current source and the inductive coupling circuitry such that at least some of the DC electrical current flows through the at least one current sense resistor to generate a current sense voltage across the at least one current sense resistor, the current sense voltage indicative of the positive and negative variations. 
     
     
         4 . The apparatus of  claim 3 , wherein the load modulation sensing circuitry comprises:
 first current sensing circuitry configured to detect the at least positive variations and to generate first digital signals in response thereto;   second current sensing circuitry configured to detect the at least negative variations and to generate second digital signals in response thereto; and   combinatory logic circuitry configured to receive and combine the first digital signals and the second digital signals to generate the signals indicative of the load modulation.   
     
     
         5 . The apparatus of  claim 4 , wherein the first current sensing circuitry comprises:
 at least one first amplifier configured to receive the current sense voltage and to generate first voltage signals having first magnitudes indicative of magnitudes of the positive variations on the DC electrical current; and   first comparator circuitry configured to receive the first voltage signals and to generate the first digital signals in response to magnitudes of the first voltage signals being greater than or equal to a first threshold value;   
       and the second current sensing circuitry comprises:
 at least one second amplifier configured to receive the current sense voltage and to generate second voltage signals having second magnitudes indicative of magnitudes of the negative variations on the DC electrical current; and 
 second comparator circuitry configured to receive the second voltage signals and to generate the second digital signals in response to magnitudes of the second voltage signals being greater than or equal to a second threshold value, wherein the first threshold value is substantially equal to a first average DC voltage output of the at least one first amplifier and the second threshold value is substantially equal to a second average DC voltage output of the at least one second amplifier. 
 
     
     
         6 . The apparatus of  claim 5 , wherein the first comparator circuitry is configured to compare a first scaled voltage indicative of an instantaneous magnitude of the first voltage signals to the first average DC voltage output of the at least one first amplifier and the second comparator circuitry is configured to compare a second scaled voltage indicative of an instantaneous magnitude of the second voltage signals to the second average DC voltage output of the at least one second amplifier. 
     
     
         7 . The apparatus of  claim 1 , wherein the combined first and second digital signals are indicative of backlink data received by the apparatus from the power receiving circuitry. 
     
     
         8 . The apparatus of  claim 3 , wherein the load modulation sensing circuitry comprises:
 at least one amplifier configured to receive the current sense voltage and to generate voltage signals having magnitudes indicative of magnitudes of the positive and negative variations on the DC electrical current;   analog-to-digital converter (ADC) circuitry configured to detect the voltage signals; and   digital processing circuitry configured to detect the positive and negative variations and to generate, in response thereto, the signals indicative of the load modulation.   
     
     
         9 . The apparatus of  claim 8 , wherein the ADC circuitry is configured to sample the voltage signals at a sampling rate. 
     
     
         10 . The apparatus of  claim 1 , further comprising controller circuitry configured to receive the signals indicative of the load modulation, to extract information therefrom, and to use the information. 
     
     
         11 . The apparatus of  claim 1 , wherein the apparatus further comprises the power transmission circuitry and at least one power supply configured to provide the DC electrical current to the power transmission circuitry. 
     
     
         12 . The apparatus of  claim 1 , wherein the apparatus comprises an external portion of a medical device, and the power receiving circuitry is within an implantable portion of the medical device configured to be implanted on or within a recipient's body with tissue between the external portion and the implantable portion. 
     
     
         13 . The apparatus of  claim 12 , wherein the medical device comprises an acoustic prosthesis. 
     
     
         14 . A method comprising:
 wirelessly transmitting power through tissue to an implant on or within a recipient's body by providing electrical current to power transmission circuitry inductively coupled to power reception circuitry of the implant;   receiving a voltage indicative of variations imparted onto the electrical current by controlled adjustments of a resonant frequency and/or a resistive load of the power receiving circuitry; and   detecting the variations on the electrical current, said detecting comprising:
 in response to the voltage, generating signals indicative of negative current variations and/or positive current variations on the electrical current; and 
 deriving data from the signals. 
   
     
     
         15 . The method of  claim 14 , wherein said generating the signals comprises using analog-to-digital converter circuitry configured to sample the voltage and said deriving the data comprises using digital processing circuitry. 
     
     
         16 . The method of  claim 14 , wherein said generating the signals comprises generating a plurality of first digital pulses indicative of the negative current variations and/or generating a plurality of second digital pulses indicative of the positive current variations, and said deriving the data comprises generating a pulse train by combining the first digital pulses and the second digital pulses. 
     
     
         17 . The method of  claim 16 , further comprising:
 generating a filtered pulse train by detecting two or more pulses of the combined pulse train that are separated from one another by a time period less than or equal to a threshold time period and replacing the two or more pulses by a single pulse; and   decoding the filtered pulse train to extract information received from the implant.   
     
     
         18 . The method of  claim 16 , wherein said generating the plurality of first digital pulses comprises amplifying negative analog pulses on the voltage, comparing a negative magnitude of each amplified negative analog pulse to a negative threshold value, and generating a first digital pulse of the plurality of first digital pulses in response to the amplified negative analog pulse having a negative voltage magnitude greater than the negative threshold value and/or said generating the plurality of second digital pulses comprises amplifying positive analog pulses on the voltage, comparing a positive magnitude of each amplified positive analog pulse to a positive threshold value, and generating a second digital pulse of the plurality of second digital pulses in response to the amplified positive analog pulse having a positive voltage magnitude greater than the positive threshold value. 
     
     
         19 . An apparatus comprising:
 at least one coil driver comprising at least one current sense resistor;   at least one power transmitting coil configured to receive an electrical current from the at least one sense resistor, the at least one power transmitting coil configured to be in inductive communication with a device; and   load modulation sensing circuitry configured to detect variations of a voltage across the at least one current sense resistor.   
     
     
         20 . The apparatus of  claim 19 , wherein the load modulation sensing circuitry comprises:
 at least one amplifier configured to receive the voltage and to generate voltage signals having magnitudes indicative of magnitudes of positive and negative variations of the voltage;   analog-to-digital converter (ADC) circuitry configured to detect the voltage signals; and   digital processing circuitry configured to detect the positive and negative variations and to generate, in response thereto, signals indicative of the load modulation.   
     
     
         21 . The apparatus of  claim 19 , wherein the load modulation sensing circuitry comprises:
 first circuitry configured to detect at least negative variations of the voltage and to generate first digital signals in response thereto;   second circuitry configured to detect at least positive variations of the voltage and to generate second digital signals in response thereto; and   combinatory logic circuitry configured to receive and respond to the first digital signals and the second digital signals by generating a digital pulse train.   
     
     
         22 . The apparatus of  claim 21 , wherein the first circuitry is configured to generate first analog signals having first magnitudes indicative of magnitudes of positive variations of the voltage and to generate the first digital signals in response to the magnitudes of the positive variations of the voltage being greater than or equal to a first threshold value, and the second circuitry is configured to generate second analog signals having second magnitudes indicative of magnitudes of negative variations of the voltage and to generate the second digital signals in response to the magnitudes of the negative variations of the voltage being greater than or equal to a second threshold value.